Voice is one of the most defining outward characteristics of an individual, yet many people don't realize the powerful effect of their voices.

"Your voice can be a dagger or a comforter, a well of confidence or a spring of doubt," said University of Iowa speech pathology and audiology professor Ingo R. Titze. "In a world in which insults and vocal intimidation are now practiced as a social skill, a warm, soothing voice can set you apart from others."Titze, who earned a Ph.D. from Brigham Young University in physics, told BYU students Tuesday that they can control the image they project by training their voices. Not only does discovering the influence of voice have an effect on others, but it also can lead one to take action to preserve his or her voice, he said.

"We can sweeten our voices by changing our pitch, by pausing longer and waiting for replies, by asking friends if there is a raspiness, nasality or other annoyance in our voice, by caressing more with our words," Titze said.

"This type of vocal caressing, being more expressive with pitch, loudness and voice quality variation is also healthy for your larynx."

The larynx is driven by both the speech motor system (where the tongue, lips and other speech articulators work to produce voice communication) and the limbic system (where emotions and environment contribute to the production of sounds like cries, grunts, shouts, moans and laughter).

While some scientists believe the speech motor and limbic systems operate independently of one another, others say they are intertwined and compete for the use of the larynx and lungs.

When a person chokes up or sobs while speaking, it's likely that the two systems are at work simultaneously.

"That's poor speech, but extraordinary vocal communication," Titze said. "Some listeners are enraptured by it, others are embarrassed by it. Emotions talk to emotions."

Whether the speech motor system can work without the limbic system, it's apparent that the larynx plays a central and multidimensional role in the body. The larynx is situated in the middle of the neck, surrounded by the body's lifelines. It's connected to several parts of the body's nervous system.

"Is it any wonder that our voice is a mirror of most of our body functions?" Titze asked.

"Voice reflects our age, gender, disease, fatigue and physical fitness."

Teachers and parents should take care to speak nourishingly because children and teenagers are particularly sensitive to voice communication. Sometimes, it's not the words that make a difference for good or bad, but the tone of voice, Titze said.

Those in professions like teaching, marketing, law and public speaking need to learn how to preserve their voices, he said. Doing voice exercises can break down tensions and may have significant health benefits.

Titze's research included developing a voice simulator. The simulator, which Titze dubbed "Pavarobotti," has been programmed to sing opera numbers such as "O Sole Mio" and "Nessum Dorman."

Titze displayed a video in which the voice simulator sings with two human tenors. The singing robot more than held its own and displayed amazing range. Titze said the voice simulator research has taught him much about how the human voice works.

Simulated speech is prevalent in some of today's cars, elevators, teller machines and even appliances. And even though simulators might be able to sing nearly as well as humans, Titze doesn't expect a chorus of Pavarobottis will displace the Mormon Tabernacle Choir anytime soon.

"I hope that simulated speech and song will never replace human soundings," he said. "I have tried to make the case that vocalizing, like general body exercise, is a necessary part of life."